During the game, type 1982gonzo. In some versions, type gonzo1982. Then press the following key combinations simultaneously:

Code 			Result 
SHIFT+V 		Trace user
SHIFT+X 		Teleports selected commandos    
CTRL+I 			Invincibility 
CTRL+SHIFT+N 		Finishes mission 
CTRL+SHIFT+X		Destroy everything
Shift+F1/F2/F3/F4	Video mode

Backpack cheat:
The Diver can take two other men in his backpack. When his boat is in the water, pick it up using the hand. If you let two commandos step into the boat st the right moment, they'll go with the boat, into the backpack of the diver/spy. Now you can swim as a diver to the other side of the water, which is much less suspicious then when you use your boat. But when you die, the men you carry with you will die too! So be careful!

Enter these Level codes on the Password screen:

Mission		Code
2		4JJXB
3 		ZDD1T
4		RFF1J 
5		K4TCG 
6		DT1WN 
7		IH3W1 
8		52WJ7 
9		924BF 
10		HYBM3 
11		JF0P3 
12		4MB4D 
13		BJK4Y 
14		TI8D1 
15		XQWDC 
16		334MW 
17		VTIM3 
18		R4OJF 
19		TFCWB 
20		DDKW1